1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a Micro-Electro-Mechanical Systems (MEMS) switch and a method for manufacturing the same.
2. Description of the Related Art
Electronic systems for use in a high frequency bandwidth are getting slimmer, smaller, lighter, and better in performance. Ultra-small microswitches using a new technology such as micromachining are being developed to substitute for semiconductor devices such as Field Effect Transistors (FET) and pin diodes, which have been used for controlling such electronic systems.
Among radio frequency (RF) devices using MEMS technologies, most devices manufactured are switches. RF switches are frequently applied in signal transmission circuits and impedance matching circuits for use in wireless terminals and systems using micro- or millimeter-wavelength bandwidth.
In conventional MEMS switches, electrification is caused when a DC voltage is applied to a fixed switch and thus a movable electrode is attracted to a substrate due to an electrostatic attraction. As the movable electrode is attracted to the substrate, a contact member provided on the movable electrode comes into contact with a signal line provided on the substrate. The switch operates so that the switch is turned on and off as the contact member comes into contact with and is separated from the signal line in response to the voltage application.
However, MEMS switches performing their switching operations by electrostatic attraction have disadvantages as discussed below.
First, such conventional MEMS switches operate at a high driving voltage.
Second, in manufacturing the MEMS switches on a wafer, structures constituting the MEMS switches are not the same over the entire area of the wafer, that is, the uniformity of the structures manufactured in the wafer is not good.
Third, since the manufacturing method of the MEMS switches includes lots of process steps, the MEMS switches are manufactured in low yield.
Here, “uniformity” means that distances between fixed electrodes and movable electrodes in lots of cells are constant all over the wafer.
Fourth, since a contact force of the contact member to the signal line is not stable, an insertion loss also increases as the number of switching operations increases.